1. Field of the Invention
The present invention relates to methods and apparatus for use in a wellbore; more particularly the invention relates to methods and apparatus for expanding tubulars in a wellbore.
2. Background of the Related Art
The drilling, completion and servicing of hydrocarbon wells requires the use of strings of tubulars of various sizes in a wellbore in order to transport tools, provide a path for drilling and production fluids and to line the wellbore in order to isolate oil bearing formations and provide support to the wellbore. For example, a borehole drilled in the earth is typically lined with casing which is inserted into the well and then cemented in place. As the well is drilled to a greater depth, smaller diameter strings of casing are lowered into the wellbore and attached to the bottom of the previous string of casing. Tubulars of an ever-decreasing diameter are placed into a wellbore in a sequential order, with each subsequent string necessarily being smaller than the one before it. In each instance, a sufficient amount of space must exist in an annular area formed between the tubulars in order to facilitate the fixing, hanging and/or sealing of one tubular from another or the passage of cement or other fluid through the annulus. Typically, when one tubular is hung in a wellbore, a slip assembly is utilized between the outside of the smaller tubular and the inner surface of the larger tubular therearound. One such assembly includes moveable portions which are driven up cone-shaped members to affix the smaller tubular to the larger tubular in a wedging relationship.
Increasingly, lateral wellbores are created in wells to more fully or effectively access hydrocarbon bearing formations. These lateral wellbores are formed off of a vertical wellbore and are directed outwards through the use of a diverter, like a whipstock. After the lateral wellbores are formed, they are typically lined with a tubular creating a junction between the tubulars lining the vertical and lateral wellbores. The junction must be sealed to maintain an independent flow path in and around the wellbores. While technologies have effectively provided means for forming and lining the lateral wellbore, an effective sealing solution for the junction created at the intersection of the vertical and lateral wellbores remains a problem.
There is a need, therefore, for apparatus and methods to quickly and easily expand a tubular in a wellbore to a given diameter. There is a further need for apparatus and methods which permit a tubular of a certain diameter to be inserted into a wellbore and to subsequently permit the diameter of that tubular to be expanded in the wellbore to maximize the fluid or tool carrying capacity of the tubular or to cause the outer surface of the tubular to interfere with the inner surface of a larger tubular therearound. There is yet a further need, for methods and apparatus for expanding tubulars in a wellbore which permit one tubular to be expanded into a window formed in another tubular to create a sealing relationship. There is yet a further need for methods and apparatus permitting a tubular to be expanded into an opening in a larger tubular therearound to create a sealing relationship.
The present invention relates to methods and apparatus for expanding tubulars in a wellbore. In one aspect of the invention, an expansion tool with hydraulically actuated, radially expandable members is disposed on a string of coil tubing. The string of coil tubing is inserted into the wellbore from a reel at the surface of the well. In addition to providing transportation for the expansion tool into the wellbore, the coil tubing provides a source of hydraulic fluid from the surface of the well to actuate the expansion tool therebelow. A mud motor disposed on the coil tubing string above the expansion tool provides the expansion tool with rotary power. With the expansion tool lowered into a wellbore to a predetermined location within a tubular therearound, the expansion tool may be actuated and rotated and some portion of the tubular therearound expanded to a larger diameter.
In another aspect of the invention, an apparatus includes an expansion tool, a tractor and a mud motor disposed on a coiled tubing string. The tractor, with radially expandable members actuated by hydraulic fluid from the coiled tubing and rotated by the mud motor, propels the apparatus axially in the wellbore while the expansion tool expands the tubular therearound through radial force and rotation. In use, the apparatus is lowered into the wellbore from the surface of the well to a predetermined depth within a tubular therearound. Thereafter, the tractor is actuated by the mud motor and provides axial movement of the apparatus while the expansion tool rotates and expansion members thereupon are actuated to increase the diameter of a tubular therearound.
In another aspect of the invention, an apparatus is provided having an electric motor, at least one pump and a hydraulic fluid reservoir disposed in a housing with an expansion tool disposed therebelow. The apparatus is run into the well on a wireline which provides support for the weight of the apparatus and electrical power for the components therein. More specifically, the apparatus is lowered into a tubular in a wellbore to a predetermined depth. Thereafter, electric power supplied to the motor operates the pump to provide pressurized fluid to actuate the expansion tool and a shaft extending from the pump provides rotational power to the expansion tool.
In another aspect of the invention, the apparatus further includes a tractor run into the well on wireline along with the expansion tool and the housing enclosing the pump reservoir and motor. The electrical motor operates the pump which provides a source of pressurized fluid to the tractor and the expansion tool. Rotational force to the expansion tool and tractor is provided by an output shaft from the electric motor. In use, the tractor imports axial movement to the apparatus in the wellbore while the expansion tool rotates and expandable members thereupon increase the diameter of the tubular therearound.
In yet another aspect of the invention, an apparatus includes a housing with two pumps and an electric motor disposed therein. Disposed above the housing is a tractor and disposed below the housing is an expansion tool. The apparatus is run into the wellbore on wireline which provides support for the weight of the apparatus and electrical power for the electric motor. In use, the electric motor provides power to an upper pump which actuates radially expandable members of the tractor thereby imparting axial movement to the apparatus in the wellbore. Additionally, the electric motor provides power to a lower pump which actuates the expansion tool therebelow. Both the expansion tool and tractor rotate to move the assembly axially in the wellbore and expand a longitudinal section of the tubular when desired.
In a further aspect of the invention a method is provided using the apparatus of the present invention to expand one tubular into a window formed in another tubular to effect a substantially sealed junction between a vertical and lateral wellbore.